Sun and stars’ daily trek form Hawaiian compass

A keenly developed ability to read the night sky helped early Polynesians find their way from island to island across the Pacific, and ultimately to Hawaii. Under the leadership of the Polynesian Voyaging Society, modern Hawaiian voyagers have rediscovered this knowledge and continued to develop and share it with a broader community. The recent completion of the three-year Malama Honua Worldwide Voyage by the voyaging canoe Hokule‘a underscores the timeless relevance of this indigenous system of celestial navigation.

Traditional oceanic wayfinding, or non-instrument navigation, needs to perform three essential functions: (1) to orient and set direction for the vessel, (2) to identify the vessel’s position at sea, and (3) to make landfall. The tool used by modern-day navigators aboard the Hokule‘a is the Hawaiian Star Compass.

A sidereal (“star”) compass, the modern Hawaiian Star Compass is based on traditional models of orientation and direction setting. The framework for the star compass is a circle whose edge represents the visual horizon, where sky touches land or sea. The user, at the center of the circle, is represented by the image of a bird in flight, reinforcing the concept that a bird is never lost, but always guided by an internal compass that leads to distant landfalls.

The circle is divided into four principal directions that intersect at 90-degree angles, east-west and north-south. The primary celestial body used to establish direction in the star compass is our daytime star, the sun. The sun travels a yearly cycle, rising north of east during our northern hemisphere summer, and then rising south of east during our winter.

The Hawaiian word for east, hikina, means “to arrive” and references the horizon where stars first arrive and begin their nightly climb into the sky. As they move across the sky and transit the meridian they begin their descent toward the west, re-entering the horizon to disappear from sight.

The Hawaiian word for west, komohana, means “to enter.” With the Hawaiian Star Compass these are the first two cardinal directions to establish: hikina and komohana.

A bird flying with its tail pointed toward hikina, or east, would have its beak facing komohana, west. Its right wing would extend towards the edge of the circle we call akau, north, and its left wing would point to hema, south. An imaginary line drawn between north and south, the meridian, is the boundary between eastward-rising and westward-descending stars.

The compass circle is divided into 32 segments called star houses, each of which occupies an 11.25-degree arc of the circle. To enable the setting of course and direction, the navigator memorizes the houses where key stars rise and set. The star compass diagram includes the names of the first four star houses.

October’s night sky

The hour of 8 p.m. is a great time to stargaze, since it is usually nice and dark but not too late. Throughout October, Kahuinakoluho‘o­kele (The Navigator’s Triangle) will be high and bright in the sky at this time. Comprised of three stars — Humu (Altair), Keoe (Vega), and Pira‘etea (Deneb) — the triangle stands out against the band of our Milky Way galaxy. These three stars symbolize the Pacific Island groups that define Polynesia: Humu representing Aotearoa (New Zealand), Keoe representing Rapa Nui (Easter Island), and Pira‘etea representing Hawaii. The triangle also forms one part of the Hawaiian star family Manaiakalani (Maui’s fishhook).

In the northeastern part of the sky, observers can see the faint Andromeda galaxy. First locate the bright “W” shape of ‘Iwakeli‘i (Cassiopeia) and look about 15 degrees south of its lowest, brightest star. To the naked eye, the galaxy looks like a small, blurry smudge, but this is the farthest that humans can see with the naked eye — about 2.5 million light years away. Andromeda is the closest galaxy to our Milky Way. Gravitationally, the two galaxies are moving closer together and are set to collide in a few billion years.

Throughout October, the planet Saturn will be faintly visible in the southeastern sky in the early evening. Through even a small telescope, observers can spy Saturn’s famous rings. These rings were observed in great detail by NASA’s Cassini spacecraft, which just finished its 13-year long orbit on Sept. 15, after groundbreaking research supported in part by observations performed at Hawaii-based telescopes on Maunakea. Saturn will set just before 10:30 p.m. at the start of October, but as the month goes on, it will set earlier, around 8:30 p.m. by Oct. 31.

Starting in mid-October, the Orionid meteor shower will decorate our skies. This annual meteor shower occurs from Oct. 16 to 27 and is made up of debris left from Halley’s comet.

At its peak on Oct. 21, it will produce about 20 meteors, or shooting stars, per hour.

Early-morning observation

With the sun rising just after 6 a.m. in October, the hours of 4 and 5 a.m. will be nice and dark for early-rising observers. In these morning hours the shape of Kaheiheionakeiki (Child’s Cat’s Cradle), which shares the same stars as Orion the Hunter, will be high up in the southern part of the sky. The first star to rise in Orion’s belt is known as Melemele (Mintaka); it rises exactly east and is used as a marker for the star compass house of hikina.

Before the sun rises, the bright planet Venus and the red planet Mars will rise in the east. At the start of the month these two planets will appear close together and will even be in conjunction on Oct. 5, with a separation of less than 1 degree. At the start of the month, both planets will rise just before 5 a.m.; then Venus will rise later, and the planets will slowly move apart. By month’s end, Mars will rise around 4 a.m., but Venus will not rise until about an hour later.

The planet Venus is often referred to as “the morning star,” as it is one of the last objects to fade from our sky at daybreak. Venus’ thick atmosphere reflects a significant amount of light, making it one of the brightest objects in the sky. Through a pair of binoculars or a telescope, observers can see Venus waxing and waning, just as the moon does. This happens because Venus is closer to the sun than Earth is, and thus exhibits constant shifts in the phases of its daytime and nighttime sides as it orbits the sun.

At the beginning of the month, observers will be able to catch a sliver of Venus’ night side; this sliver will slowly get smaller as the month goes on.